U.S. patent application number 13/795893 was filed with the patent office on 2013-09-19 for sheet conveying device and image forming apparatus.
This patent application is currently assigned to Ricoh Company, Limited. The applicant listed for this patent is Yuji KARIKUSA. Invention is credited to Yuji KARIKUSA.
Application Number | 20130241141 13/795893 |
Document ID | / |
Family ID | 49156915 |
Filed Date | 2013-09-19 |
United States Patent
Application |
20130241141 |
Kind Code |
A1 |
KARIKUSA; Yuji |
September 19, 2013 |
SHEET CONVEYING DEVICE AND IMAGE FORMING APPARATUS
Abstract
A sheet conveying device includes a shift unit. The shift unit
includes a gate member configured to align a recording medium being
conveyed thereto by causing a leading end of the recording medium
to abut against the gate member so that part of the recording
medium bends to form a curved portion; a pair of registration
rollers configured to convey the recording medium aligned by the
gate member at a predetermined timing, the pair of registration
rollers including a driving roller and a driven roller, the driving
roller having a rotating shaft coaxial with a rotational central
shaft of the gate member; and a drive transmitting unit configured
to transmit rotational drive from a drive unit to the driving
roller, the drive transmitting unit being disposed on an end side
of the rotating shaft of the driving roller.
Inventors: |
KARIKUSA; Yuji; (Ibaraki,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KARIKUSA; Yuji |
Ibaraki |
|
JP |
|
|
Assignee: |
Ricoh Company, Limited
Tokyo
JP
|
Family ID: |
49156915 |
Appl. No.: |
13/795893 |
Filed: |
March 12, 2013 |
Current U.S.
Class: |
271/227 ;
271/229 |
Current CPC
Class: |
B65H 2511/222 20130101;
B65H 2511/216 20130101; B65H 2511/222 20130101; B65H 5/062
20130101; B65H 9/004 20130101; B65H 7/08 20130101; B65H 9/00
20130101; B65H 2404/1424 20130101; B65H 2701/1311 20130101; G03G
15/6567 20130101; B65H 2701/1311 20130101; B65H 9/06 20130101; B65H
2403/514 20130101; B65H 2511/216 20130101; B65H 2220/11 20130101;
B65H 2220/02 20130101; B65H 2220/01 20130101; B65H 2220/02
20130101; B65H 2220/11 20130101; B65H 9/166 20130101; G03G 15/6564
20130101 |
Class at
Publication: |
271/227 ;
271/229 |
International
Class: |
B65H 9/00 20060101
B65H009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 16, 2012 |
JP |
2012-060442 |
Claims
1. A sheet conveying device comprising: a shift unit including a
gate member configured to align a recording medium being conveyed
thereto by causing a leading end of the recording medium to abut
against the gate member so that part of the recording medium bends
to form a curved portion, a pair of registration rollers configured
to convey the recording medium aligned by the gate member at a
predetermined timing, the pair of registration rollers including a
driving roller and a driven roller, the driving roller having a
rotating shaft coaxial with a rotational central shaft of the gate
member, and a drive transmitting unit configured to transmit
rotational drive from a drive unit to the driving roller, the drive
transmitting unit being disposed on an end side of the rotating
shaft of the driving roller; a shift control unit configured to
hold the shift unit so that the shift unit is movable in a
direction orthogonal to a conveying direction of the recording
medium; and a rotation control unit configured to hold the shift
unit so that the shift unit is rotatable about the drive
transmitting unit as pivotal center in the conveying direction of
the recording medium.
2. The sheet conveying device according to claim 1, further
comprising a fixing unit configured to hold the shift unit rotated
in the conveying direction of the recording medium so as to allow
the shift unit to move by the shift control unit.
3. The sheet conveying device according to claim 1, wherein the
drive transmitting unit includes a first gear for driving the
rotating shaft of the driving roller, the sheet conveying device
further comprises a second gear for transmitting a drive force to
the first gear, the first gear and the second gear each are a spur
gear, and the drive transmitting unit has rotational center formed
at an engagement portion in the first gear with the second
gear.
4. The sheet conveying device according to claim 1, wherein at
least one of a shift amount of the shift unit controlled by the
shift control unit and a rotation amount of the shift unit
controlled by the rotation control unit are to be set manually.
5. The sheet conveying device according to claim 1, further
comprising: a detector configured to detect a position of the
recording medium in a direction orthogonal to the conveying
direction of the recording medium, the detector being disposed
downstream of the shift unit in the conveying direction; and a
shift control driving unit configured to control the shift control
unit, wherein the shift control driving unit calculates a shift
amount of the shift unit based on a value detected by the detector
and moves the shift unit by the calculated shift amount.
6. The sheet conveying device according to claim 5, further
comprising a rotation control driving unit configured to control
the rotation control unit, wherein the rotation control driving
unit calculates an angle adjustment amount of the shift unit based
on the value detected by the detector and rotates the shift unit by
the calculated angle.
7. The sheet conveying device according to claim 6, wherein the
shift control driving unit calculates the shift amount by adding or
subtracting a deviation amount in the direction orthogonal to the
conveying direction of the recording medium, the deviation amount
arising from the rotation of the shift unit based on the angle
adjustment amount calculated by the rotation control driving
unit.
8. The sheet conveying device according to claim 1, further
comprising: a pair of paper feeding rollers configured to convey
the recording medium, the pair of paper feeding rollers being
disposed upstream of the shift unit in the conveying direction; and
a pair of timing rollers configured to convey the recording medium,
the pair of timing rollers being disposed downstream of the shift
unit in the conveying direction.
9. An image forming apparatus comprising the sheet conveying device
according to claim 1.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application claims priority to and incorporates
by reference the entire contents of Japanese Patent Application No.
2012-060442 filed in Japan on Mar. 16, 2012.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention generally relates to a sheet conveying
device and an image forming apparatus.
[0004] 2. Description of the Related Art
[0005] In an image forming apparatus, such as a laser printer,
sheets, such as transfer paper, loaded in a feeding device are fed
off one by one and conveyed onto a transfer position. At the
transfer position, a position of a toner image formed on, for
example, a photosensitive drum or a photosensitive belt, and a
transfer position on the sheet side are aligned with each other, so
that the toner image is transferred onto the sheet. After the
transfer, the sheet is output as a reproduction having the toner
image fixed therein.
[0006] With the aim of transferring the image at a correct position
relative to the sheet, such an image forming apparatus includes a
registration mechanism that aligns a sheet feeding timing with a
timing at which the image arrives at the transfer position.
[0007] A known configuration for a registration mechanism (for
example, Japanese Utility Model Application Laid-open Publication
No. S64-000555) includes a gate member disposed, in a sheet
conveying direction, upstream of registration rollers used for
feeding out a sheet according to a registration timing. The gate
member can advance into, or retract from, a sheet conveying
path.
[0008] In this configuration, conveyance of the sheet is
temporarily continued with a leading end of the sheet abutted
against the gate member to thereby bend part of the sheet and form
a curved portion. This enables the leading end of the sheet in
which the curved portion is formed to advance toward a nip between
the registration rollers by using an action to extend the curved
portion by a shape restoring force of the sheet generated when the
gate member retracts from the sheet conveying path.
[0009] Use of the shape restoring force of the sheet allows a
clamping position of the leading end of the sheet by the
registration rollers to be uniform at all times among different
sheets. This enables an image position arrival timing and the sheet
feeding timing toward the transfer position to be aligned with each
other constantly among different sheets that are continuously
conveyed.
[0010] The configuration that incorporates the gate member requires
a gate member that is specially prepared in addition to the
registration rollers. This increases the number of components of
the sheet conveying device, which complicates a configuration of
the sheet conveying device and invites increased cost including
assembly.
[0011] Another arrangement has been developed in which a
registration roller includes a leading end abutment mechanism (for
example, Japanese Patent Application Laid-open No. H5-338865).
Japanese Patent Application Laid-open No. H5-338865 discloses a
configuration that includes a torque limiter interposed in a
rotating shaft of the registration roller and a gate member
disposed rotatably on the rotating shaft.
[0012] In this configuration, the gate member is operatively
associated with forward and backward rotation of the registration
roller and oscillatable between a position at which a sheet leading
end is to be positioned, specifically, a position against which the
sheet leading end is abutted, and a position at which the sheet
having the leading end abutted against the gate member can be fed
off, specifically, a retracted position.
[0013] The gate member is operatively associated with rotation of
the registration roller in a direction opposite to a sheet feeding
direction, thereby oscillating to the position at which to abut
against the sheet leading end. The gate member is operatively
associated with rotation of the registration roller in a direction
of the sheet feeding direction, thereby oscillating to the position
retracted from the abutment position. Upon collision with a sheet
conveying guide member, the gate member remains stationary at the
position with no rotation being transmitted through operation of
the torque limiter.
[0014] Japanese Patent Application Laid-open No. 2012-030971
discloses a sheet conveying device that includes a registration
roller and a gate member disposed coaxially with each other to
thereby achieve a simple configuration. The sheet conveying device
is capable of aligning the toner image on a recording medium with
the transfer position accurately and within a short time, the
recording media being conveyed at high speed and at short
intervals.
[0015] In general, in sheet conveying devices, print skew may not
be properly corrected due to, for example, a pair of registration
rollers or a gate member being out of a correct mounting position,
a warped shaft, and part-to-part variations.
[0016] Additionally, an image forming apparatus may be installed on
a distorted or warped surface. Such an image forming apparatus may
be affected by the improper mounting surface, causing a reference
line of a skew correcting mechanism to be distorted relative to an
image transfer unit or the image transfer unit itself to be
distorted, resulting in image skew.
[0017] An error in skew correction may also occur due to wear or a
change with time in a supporting member of a shaft of the pair of
registration rollers.
[0018] The image forming apparatus may also be operated to form an
image on top of a sheet on which an image has previously been
formed. In such a case, the image originally formed on the sheet
may not be square relative to the sheet, specifically, the image
may be recorded slantwise relative to the sheet. This requires that
an arrangement be made to intentionally give the sheet a
predetermined amount of inclination for its conveyance. Such an
adjustment is difficult to make, which poses a problem.
[0019] Various techniques have been developed that detect and
adjust such skew. Japanese Patent Application Laid-open No.
2001-335166, for example, discloses a paper feeding mechanism that
includes a paper feeding roller driving shaft disposed in a frame
in a manner being inclinable relative to a normal sheet conveying
direction and a changeover lever that is capable of adjusting an
inclination angle of the paper feeding roller driving shaft, the
changeover lever being oscillatably moved to thereby allow sheet
conveyance to be performed in a condition of being obliquely
supported at any desired angle. In addition, Japanese Patent
Application Laid-open No. 2009-057143 discloses a feeding device
that similarly adjusts an angle of a roller driving shaft to
thereby adjust skew in a recording medium in a direction orthogonal
to a conveying direction.
[0020] In addition, Japanese Patent Application Laid-open No.
2008-239340 and Japanese Patent Application Laid-open No.
2010-024059 each disclose a conveying device that includes an
abutment member (gate member) that blocks a conveying path of a
recording medium to thereby allow a leading end of the recording
medium to abut thereagainst and opens thereafter the conveying path
and a variable unit that varies inclination in a width direction of
the abutment member relative to a conveying direction of the
recording medium, the abutment member being inclined relative to a
registration roller.
[0021] The arrangements disclosed in Japanese Patent Application
Laid-open No. 2001-335166 and Japanese Patent Application Laid-open
No. 2009-57143, although being capable of adjusting the inclination
angle of the paper feeding roller driving shaft, have no gate
members, which makes it difficult to adjust the sheet feeding
timing. The arrangements disclosed in Japanese Patent Application
Laid-open No. 2008-239340 and Japanese Patent Application Laid-open
No. 2010-24059 do have a gate member and its inclination angle is
adjusted; however, the arrangements require a gate member in
addition to the registration roller, which increases the number of
components of the sheet conveying device. This poses problems of a
complicated configuration of the sheet conveying device and
increased cost including assembly.
[0022] In contrast, referring to Japanese Patent Application
Laid-open No. 2012-30971, the sheet conveying device is simply
structured for improved productivity by having a unit (shift unit)
supporting the gate member and a pair of clamp carriage rollers (a
pair of registration rollers). The arrangement disclosed in
Japanese Patent Application Laid-open No. 2012-30971 controls
movement of the shift unit in an axial direction (a direction
orthogonal to the sheet conveying direction) to thereby permit
lateral shift motion of the gate member. Nonetheless, the
arrangement disclosed in Japanese Patent Application Laid-open No.
2012-30971 poses a problem in that the inclination angle of the
gate member cannot be easily adjusted.
[0023] Therefore, there is a need to provide a sheet conveying
device having an arrangement in which a gate member and a pair of
registration rollers are supported by a shift unit with its
movement controlled in a direction orthogonal to a sheet conveying
direction, the arrangement enabling a simple adjustment of a gate
angle, and an image forming apparatus having the sheet conveying
device.
SUMMARY OF THE INVENTION
[0024] It is an object of the present invention to at least
partially solve the problems in the conventional technology.
[0025] According to an embodiment, there is provided a sheet
conveying device that includes a shift unit. The shift unit
includes a gate member configured to align a recording medium being
conveyed thereto by causing a leading end of the recording medium
to abut against the gate member so that part of the recording
medium bends to form a curved portion; a pair of registration
rollers configured to convey the recording medium aligned by the
gate member at a predetermined timing, the pair of registration
rollers including a driving roller and a driven roller, the driving
roller having a rotating shaft coaxial with a rotational central
shaft of the gate member; and a drive transmitting unit configured
to transmit rotational drive from a drive unit to the driving
roller, the drive transmitting unit being disposed on an end side
of the rotating shaft of the driving roller. The sheet conveying
device also includes a shift control unit configured to hold the
shift unit so that the shift unit is movable in a direction
orthogonal to a conveying direction of the recording medium; and a
rotation control unit configured to hold the shift unit so that the
shift unit is rotatable about the drive transmitting unit as
pivotal center in the conveying direction of the recording
medium.
[0026] According to another embodiment, there is provided an image
forming apparatus that includes the sheet conveying device
according to the above embodiment.
[0027] The above and other objects, features, advantages and
technical and industrial significance of this invention will be
better understood by reading the following detailed description of
presently preferred embodiments of the invention, when considered
in connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] FIG. 1 is a general configuration diagram illustrating an
image forming apparatus according to an embodiment of the present
invention;
[0029] FIG. 2 is a general configuration diagram illustrating a
sheet conveying device according to the embodiment of the present
invention;
[0030] FIGS. 3A and 3B are perspective views illustrating a
configuration of pairs of registration rollers and gate
members;
[0031] FIG. 4 illustrates cross-sectional views of the
configuration of the pairs of registration rollers and the gate
members;
[0032] FIG. 5 is a top view illustrating the sheet conveying
device;
[0033] FIG. 6 is a schematic view illustrating the pairs of
registration rollers viewed from a downstream side of a sheet
conveying path;
[0034] FIG. 7 is a schematic view illustrating members that
constitute a shift unit to integrally shift the pairs of
registration rollers in an axial direction;
[0035] FIG. 8 is a schematic view illustrating an exemplary fixing
guide;
[0036] FIG. 9 is a schematic view illustrating an exemplary shift
control driving unit;
[0037] FIG. 10 is a diagram illustrating a rotation control
unit;
[0038] FIG. 11 is a top view illustrating the sheet conveying
device during angle adjustment;
[0039] FIG. 12 is a diagram illustrating a method for adjusting
skew and a position in a width direction of a sheet fed onto the
sheet conveying device;
[0040] FIG. 13 is a diagram illustrating an axial deviation amount
during angle adjustment;
[0041] FIG. 14 is a top view illustrating the sheet conveying
device during angle adjustment by a shift unit including a
shaft;
[0042] FIG. 15 illustrates a condition in which the shaft is fixed
to a frame side plate with a bracket; and
[0043] FIG. 16 is a top view illustrating the sheet conveying
device during angle adjustment by a shift unit including a rotary
plate.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0044] Arrangements according to the present invention will be
described in detail below with reference to preferred embodiments
of the present invention illustrated in FIGS. 1 to 16.
First Embodiment
[0045] A sheet conveying device (10) according to a first
embodiment of the present invention includes a shift unit (20). The
shift unit (20) includes a gate member (14), a pair of registration
rollers (12), and a drive transmitting unit (a first gear 19).
Specifically, the gate member (14) causes a leading end of a
conveyed recording medium (sheet) to abut against the gate member
(14) so that part of the recording medium bends to form a curved
portion, thereby aligning the recording medium. The pair of
registration rollers (12) includes a driving roller (12A) and a
driven roller (12B). The driving roller has a rotating shaft (12a)
coaxial with a rotational central shaft of the gate member. The
pair of registration rollers (12) conveys the recording medium
aligned by the gate member at a predetermined timing. The drive
transmitting unit is disposed on a first end side of the rotating
shaft of the driving roller and transmits rotational drive from a
drive unit (40) to the driving roller. The sheet conveying device
10 further includes a shift control unit (for example, a shift unit
20, a fixing guide 24, and a second gear 42) that holds the shift
unit movably in a direction orthogonal to a conveying direction of
the recording medium and a rotation control unit (for example, a
shift unit 20, a fixing guide 24, and a second gear 42) that holds
the shift unit rotatably in the conveying direction of the
recording medium about the drive transmitting unit as the pivotal
center. It is noted that the figures in parentheses denote
reference numerals used in the embodiment.
[0046] Image Forming Apparatus
[0047] FIG. 1 is a schematic diagram illustrating an exemplary
image forming apparatus to which a sheet conveying device 10
according to the embodiment of the present invention is applied.
The exemplary image forming apparatus illustrated in FIG. 1 is a
full-color image forming apparatus including a plurality of image
formers disposed along an extended portion of a transfer belt used
as a transfer unit.
[0048] As illustrated in FIG. 1, this image forming apparatus 100
includes a primary transfer unit, a sheet feeding device 103, a
secondary transfer unit 104, and a sheet conveying device
(registration unit) 10. Specifically, the primary transfer unit
includes an intermediate transfer belt 102 having an extended
surface along which image formers 101 of different colors are
arrayed in juxtaposition to each other. The sheet feeding device
103 stores therein sheets, such as recording sheets. The secondary
transfer unit 104 transfers images in which one is superimposed on
another on the intermediate transfer belt all at once onto a sheet
fed from the sheet feeding device 103. The sheet conveying device
(registration unit) 10 aligns a timing at which the sheet is to be
conveyed onto the secondary transfer unit 104 with an image
position.
[0049] The image formers 101 of a plurality of colors form images
through a well-known electrophotography process in which toner
images made visible by toner of different colors are superimposed
one on top of another and transferred onto the intermediate
transfer belt 102. The sheet feeding device 103 feeds a sheet from
a cassette loaded with sheets and conveys the sheet toward the
sheet conveying device 10.
[0050] Sheet Conveying Device
[0051] FIG. 2 illustrates a configuration of the sheet conveying
device 10. The sheet conveying device 10 includes pairs of paper
feeding rollers 11, pairs of registration rollers 12 (each pair
including a driving roller 12A, a driven roller 12B), and pairs of
timing rollers 13, disposed in this order from an upstream side
toward a downstream side in a sheet conveying direction (the
direction of an arrow in FIG. 2).
[0052] The pairs of paper feeding rollers 11 and the pairs of
timing rollers 13 each include a pair of rollers having a
substantially identical diameter, disposed across a sheet conveying
path. The pairs of paper feeding rollers 11 and the pairs of timing
rollers 13 each are fixed in position by a method not illustrated
so that the sheet conveying direction extends in parallel relative
to each other.
[0053] The sheet conveying device 10 further includes gate members
14, each of the gate members 14 being disposed coaxially with the
driving roller 12A of each pair of registration rollers 12. The
gate member 14 has an abutment surface protruding to the conveying
path to thereby cause a conveyed sheet to abut against the abutment
surface, thus positioning a leading end of the sheet.
[0054] The sheet conveying device 10 further includes a contact
image sensor (CIS) 15 disposed downstream of the pairs of
registration rollers 12 and upstream of the pairs of timing rollers
13. The CIS 15 serves as a detector that detects a position in a
direction orthogonal to the sheet conveying direction.
[0055] In addition, a portion of the conveying path between the
pairs of paper feeding rollers 11 and the pairs of registration
rollers 12 has a lower conveying guide 16 and an upper conveying
guide 17. Specifically, the lower conveying guide 16 is disposed
substantially in parallel with a tangential direction extended from
a nip between each pair of paper feeding rollers 11. The upper
conveying guide 17 faces the lower conveying guide 16 and has part
of an extension bulging away from the lower conveying guide 16. The
bulge of the upper conveying guide 17 is a portion at which a
curved portion produced when part of the sheet is bent is
located.
[0056] Pairs of Registration Rollers/Gate Members
[0057] The pairs of registration rollers 12 each include the
driving roller 12A (gate side roller) and the driven roller 12B
(feeding roller) disposed on the lower side and the upper side,
respectively, across the sheet conveying path.
[0058] FIGS. 3A and 3B illustrate in detail the driving roller 12A.
As illustrated in FIGS. 3A and 3B, the driving roller 12A is
provided with the gate member 14 coaxially supported adjacent to
the axial end of a roller shaft 12a.
[0059] As illustrated in FIG. 4, the gate member 14 has a stopper
14A at a part in a peripheral direction thereof. The stopper 14A
protrudes to the inside of the sheet conveying path and a leading
end of a sheet abuts against the stopper 14A to be stopped. A guide
surface 14B is formed on a part continuous with the stopper 14A,
the guide surface 14B having an outside diameter identical to that
of the driving roller 12A.
[0060] As illustrated in (A) of FIG. 4, a condition in which a
trailing end of the stopper 14A is disposed on a line that connects
the rotational center of the driving roller 12A and that of the
driven roller 12B disposed on the side opposite to the driving
roller 12A across the sheet conveying path is set as an initial
position in which the leading end of the sheet is abutted against
and stopped by the stopper 14A. The trailing end of the stopper 14A
can be moved to a retracted position to which the trailing end of
the stopper 14A is retracted from the sheet conveying path through
rotation of the gate member 14.
[0061] The leading end of the sheet can abut against the stopper
14A at a position upstream of a nip between the rollers in the
sheet conveying direction. The leading end of the sheet can thus be
abutted and stopped before entering the nip.
[0062] The sheet that is about to enter the nip is therefore yet to
be clamped, so that the sheet can be made easy to move for
correction of skew that indicates inclination of the sheet. When
the leading end of the sheet abuts against the stopper 14A, the
sheet bends to be deformed into a curved shape. If the sheet
continues to be fed out, moment about the leading end portion in
abutment with the stopper 14A causes the sheet to rotate in a
direction of eliminating the skew. This results in the entire area
of the leading end of the sheet abutting against the stopper 14A,
so that sheet skew can be corrected.
[0063] The guide surface 14B has the outside diameter identical to
that of the driving roller 12A. As a result, referring to (B) of
FIG. 4, the guide surface 14B, being positioned upstream of the nip
position of the rollers in the sheet conveying direction with the
stopper 14A in the initial position, can form a wedge-shaped space
with a peripheral surface of the driven roller 12B. This allows the
leading end of the sheet advancing toward the pairs of registration
rollers 12 to be easily guided toward the nip between the rollers,
which achieves a function of facilitating abutment against the
stopper 14A.
[0064] Preferably, the guide surface 14B is formed with a low
friction surface in order for the guide surface 14B to exhibit a
function of facilitating guiding also when the leading end of the
sheet slidingly moves therealong.
[0065] As illustrated in FIG. 3B, the driven roller 12B has a void
portion (denoted by N in FIG. 3B) at a part in a peripheral
direction thereof, specifically, at a position opposed to the
stopper 14A of the gate member 14. The void portion is shaped so as
to be opposed to the guide surface 14B in a condition of not
interfering with the stopper 14A when the gate member 14 is in the
initial position after several rotations through an outside
diameter ratio.
[0066] Consequently, in addition to the abutment and stop function
for the leading end of the sheet achieved by the stopper 14A, the
gate member 14 also has a function of enlarging a clamping width
relative to the sheet because of the outer peripheral surface of
the driven roller 12B being capable of abutting on the guide
surface 14B.
[0067] Being capable of enlarging the clamping width produces an
effect of smoothing movement of the sheet in the width direction,
while preventing the sheet from being damaged, specifically, being
torn by suppressing concentration of a clamping force during a
shift adjustment that means moving the position of the sheet in the
width direction.
[0068] As illustrated in FIG. 2, the outside diameter of the
driving roller 12A in each pair of registration rollers 12 is set
as described below with reference to a distance between a nip
position between each pair of registration rollers 12 and a nip
position between each pair of timing rollers 13.
[0069] Let D be the outside diameter of the driving roller 12A in
each pair of registration rollers 12 and T be the distance between
the nip between each pair of timing rollers 13 and the stopper 14A
of each gate member 14 in the initial position. Then, a
relationship of T<.pi.D holds.
[0070] This results in the following. Specifically, the leading end
of the sheet reaches the nip position between each pair of timing
rollers 13 during one rotation of the driving roller 12A and the
sheet continues to be fed out during the time in which a difference
is produced between a peripheral length and the distance between
the nip positions. The reason for setting such a difference is to
allow the leading end of the sheet to reliably reach the nip
between each pair of timing rollers 13.
[0071] The driving roller 12A is set to rotate continuously in one
direction. The driving roller 12A is, however, subject to rotation
control so as to be brought to a temporary stop substantially
simultaneously when or after the stopper 14A of the gate member 14
reaches the initial position at which the leading end of the sheet
is abutted thereagainst and stopped thereby in a rotation process,
and so as to start rotating as soon as the leading end of the sheet
abuts thereagainst.
[0072] Shift Control Unit
[0073] A shift adjustment of the sheet will be described below. The
shift adjustment refers to moving the sheet in the width direction
in order to align an image width central position in a direction
perpendicular to the sheet conveying direction with a central
position in the sheet width direction (lateral shift). The
following describes a configuration of the shift control unit that
makes the shift adjustment.
[0074] FIG. 5 is a top view illustrating the sheet conveying device
10 illustrated in FIG. 2. FIG. 6 is a schematic view illustrating
the pairs of registration rollers 12 viewed from a downstream side
of the sheet conveying path. FIG. 7 is a schematic view extracting
members that constitute a shift unit 20 to integrally shift the
pairs of registration rollers 12 in the axial direction in the
schematic view illustrated in FIG. 6.
[0075] Each of the pairs of paper feeding rollers 11, the pairs of
registration rollers 12, and the pairs of timing rollers 13 of the
sheet conveying device 10 has a roller shaft supported in frame
side plates 18A, 18B at right and left. It is noted that, in the
example illustrated in FIG. 5, the gate members 14 are disposed at
a total of six places, specifically, at both axial ends of each
driving roller 12A and ends of a shift unit frame body 21 (although
omitted in FIGS. 6 and 7).
[0076] In addition, a first gear 19 is provided as a drive
transmitting part that rotatably drives the shaft 12a of the pairs
of registration rollers 12 to thereby rotatably drive the driving
rollers 12A and the driven rollers 12B. The first gear 19 is a spur
gear. It is further noted that the driven roller 12B is supported
by a shaft 12b.
[0077] As illustrated in FIG. 6, the pairs of registration rollers
12 (the driving rollers 12A, the driven rollers 12B, the shafts
12a, 12b) and the gate members 14 are housed and retained in the
shift unit frame body 21 so as to be capable of axially shifting
along the shaft 12a. It is noted that reference numerals 21a, 21b
denote bearings.
[0078] As illustrated in FIG. 7, the first gear 19 and the shaft
12a also form part of the shift unit 20, shifting axially. This
results in an arrangement in which a second gear 42 that meshes
with the first gear 19 exhibits good sliding property.
[0079] Preferably, a guide plate 25 is disposed at a lower portion
of the shift unit 20. As illustrated in FIG. 6, ball bearings 23a,
23b disposed on the underside of the shift unit frame body 21 are
slidable along the guide plate 25.
[0080] Referring further to FIGS. 5 and 6, the shift unit frame
body 21 is fixed to the frame side plate 18B of the conveying path
via a fixing guide 24 and thereby positioned in the conveying
direction. The shift unit frame body 21 is positioned in the
direction orthogonal to the conveying direction in a condition of
being capable of shifting by a predetermined shift amount.
[0081] FIG. 8 illustrates an exemplary configuration of the fixing
guide 24. The fixing guide 24 journals the shaft 12a slidably in an
axial direction and inclinably through rotation control to be
described later with a plain bearing 26. The fixing guide 24 is
fixed to the frame side plate 18B with screws 24a that are to be
tightened in slots 24b. The fixing guide 24 can be adjustably moved
in the sheet conveying direction according to the shape of the
slots 24b. The frame side plate 18B has a hole to accommodate
therein the shaft 12a and threaded holes.
[0082] A screw and a spring may, instead, be used to permit
adjustment of the position of the shaft 12a in the direction
orthogonal to the conveying direction through a turning amount of
the screw. Alternatively, the frame side plate 18B may have slots
in which the fixing guide 24 is adjustably moved in the sheet
conveying direction.
[0083] Shift Amount Adjustment (1)
[0084] The shift amount of the shift control unit can be adjusted
to any value desired by a user. The shift amount may be, for
example, corrected based on a print result. In this manual
adjustment, the shaft 12a and the frame side plate 18B (or the
fixing guide 24) may, for example, be graduated and the position of
the shaft 12a may be adjusted to thereby adjust the shift amount of
the shift unit 20.
[0085] Shift Amount Adjustment (2)
[0086] Preferably, a shift control driving unit may also be
provided. The shift control driving unit calculates a shift
adjustment amount based on a value detected by the CIS 15, thereby
driving the shift control unit. The following describes an
exemplary shift control driving unit. The shift control driving
unit may have any configuration as long as the configuration
enables the shift unit 20 to be shifted in the axial direction. The
shift control driving unit may be, for example, configured to
include an urging unit (spring) and a cam as described in Japanese
Patent Application Laid-open No. 2008-297076 and Japanese Patent
Application Laid-open No. 2008-50069.
[0087] The shift control driving unit may, for example, include a
cam, a shift motor, and a control unit. Specifically, the cam is
intended to move axially the shift unit 20 that includes the pairs
of registration rollers 12 based on a detection result from the CIS
15 for detecting the position of the sheet in the width direction.
The shift motor assumes a driving source for driving the cam. The
control unit controls a drive amount of the shift motor based on
the detection result from the CIS 15.
[0088] The cam driven by the shift motor has a cam profile that
results in the shift unit being moved axially. The cam shifts the
shift unit 20 axially with an amount corresponding to a rotational
phase of the shift motor, so that the center of the sheet in the
width direction and the position of the image in the width
direction can be adjusted. The required shift amount is calculated
based on the position in the direction orthogonal to the sheet
conveying direction detected by the CIS 15.
[0089] The shift control driving unit may alternatively be
configured, for example, as illustrated in FIG. 9. A shift control
driving unit 30 includes a control unit not illustrated, a sensor
31, an eccentric cam 33, and a sensor plate 34. Specifically, the
sensor 31 detects a home position of the shift unit 20 and a moving
amount corresponding to the adjustment amount calculated by the CIS
15. The eccentric cam 33 is rotated by a driving source (stepping
motor) 32. The sensor plate 34 is mounted coaxially with the
eccentric cam 33. The sensor plate 34 has a slit for allowing the
sensor 31 to detect the moving amount. The eccentric cam 33 is
clamped and held between bracket mechanisms (the ball bearings 23a
and 23b in FIG. 6) attached to the shift unit 20. The shift control
driving unit 30 can thereby move the shift unit 20 horizontally
relative to the conveying direction, as translated from rotation of
the eccentric cam 33.
[0090] Rotation Control Unit
[0091] The following describes adjustment of a gate angle of the
shift unit 20, specifically, the pairs of registration rollers 12
and the gate members 14. The sheet conveying device 10 according to
the embodiment of the present invention includes the rotation
control unit that is capable of rotating the shift unit 20 about a
predetermined pivot as a reference. The following describes a
configuration of the rotation control unit that adjusts the gate
angle.
[0092] As illustrated in FIG. 5, the pairs of registration rollers
12 are rotated as follows. Specifically, drive from a motor 40 as a
driving source drives a gear train 41 and the gear (called the
second gear) 42. Further, the drive of the second gear 42 is
transmitted to the first gear 19 mounted coaxially with the pairs
of registration rollers 12, thus rotating the pairs of registration
rollers 12. It is noted that the first gear 19 and the second gear
42 each are a spur gear.
[0093] As illustrated in FIG. 6, the shaft 12a of the driving
rollers 12A of the pairs of registration rollers 12 is fixed by the
bearings 21a, 21b rotatably relative to the shift unit frame body
21. The shaft 12a is further fixed by, for example, the plain
bearing 26 slidably relative to the fixing guide 24. In addition, a
regulating member 22 that restricts a sliding amount is mounted on
the shaft 12a.
[0094] FIG. 10 is a diagram for illustrating the rotation control
unit. The pairs of registration rollers 12 are fixed such that a
second end side of the shaft 12a is moved in the conveying
direction with an engagement portion between the first gear 19 and
the second gear 42 as a pivot. This allows the shift unit 20 to be
fixed at a position at which the shift unit 20 is moved by a
predetermined angle relative to the sheet conveying direction. This
allows an abutment surface angle of the gate member 14 (gate angle)
to be adjusted to any angle relative to the conveying
direction.
[0095] The first gear 19 and the second gear 42 are spur gears and
the engagement portion therebetween is configured such that there
is a sufficient clearance between a tooth tip and a tooth bottom.
As illustrated in FIG. 10, the first gear 19 and the second gear 42
are configured such that rotation by a maximum movable angle
.theta.max does not impede meshing engagement among the gear train
for transmitting a drive force. Forming the drive transmitting unit
with the gears as described above enables the gate angle to be
adjusted over a range of the clearance between the gears.
[0096] Referring to FIG. 10, let .+-..theta..degree. be the movable
angle range of the shift unit 20, H be the width of the first gear
19, and h be the width of the second gear 42, and if H>h is
satisfied, then a relationship between a clearance t between the
first gear 19 and the second gear 42 and the maximum movable angle
may be given by Equation (1).
.theta.max=tan.sup.-1(t/h) (1)
[0097] Therefore, referring to FIG. 11, movement by an angle
.theta..sub.1 (<.theta..sub.max) does not result in the tooth
tip and the tooth bottom of the first gear 19 and the second gear
42 contacting each other. Movement of the shift unit 20 by the
angle .theta..sub.1 does not pose any sliding property problem,
enabling a shift operation.
[0098] Rotation Angle Adjustment (1)
[0099] An angle adjustment amount of the rotation control unit can
be adjusted to any value desired by a user. The angle adjustment
amount may be, for example, corrected based on a print result. This
manual adjustment may be made by, for example, adjusting tightening
positions of the screws 24a in the fixing guide 24 illustrated in
FIG. 8 to thereby change the mounting position of the fixing guide
24 on the frame side plate 18B. This allows the angle adjustment
amount of the shift unit 20 to be adjusted. At this time,
preferably, the fixing guide 24 is, for example, graduated and the
angle adjustment amount can be adjusted. In addition, the plain
bearing 26 of the fixing guide 24 allows the shift unit 20 to be
subject to shift control in a condition of being rotated.
[0100] Rotation Angle Adjustment (2)
[0101] Preferably, a rotation control driving unit may also be
provided. The rotation control driving unit calculates the angle
adjustment amount based on a value detected by the CIS 15, thereby
driving the rotation control unit. The rotation control driving
unit may, for example, be a mechanism that allows the fixing guide
24 to reciprocate in the sheet conveying direction and to be fixed
at any position. A moving mechanism may incorporate, for example, a
stepping motor, a gear, and an eccentric cam to adjust displacement
and a spring or a stepping motor to fix in position through
energization.
[0102] Exemplary Sheet Conveyance
[0103] The following describes exemplary sheet conveyance performed
by the sheet conveying device 10 described heretofore. FIG. 12 is a
diagram illustrating a method for adjusting skew and a position in
the width direction of a sheet fed from the sheet feeding device
103 onto the sheet conveying device 10.
[0104] The sheet P conveyed along a conveying path not illustrated
is abutted against the gate members 14 by the pairs of paper
feeding rollers 11. The sheet P is further fed on and a curved
portion is thereby formed therein, which corrects skew and
longitudinal registration in the sheet P.
[0105] At a predetermined timing thereafter, the gate members 14
and the pairs of registration rollers 12 are simultaneously made to
start rotating, so that the sheet P in a corrected attitude is
clamped between the pairs of registration rollers 12 and conveyed
downstream.
[0106] The position in the width direction of the sheet P conveyed
downstream is detected by the CIS 15. With the sheet P clamped
between the pairs of registration rollers 12, the shift unit 20 is
subject to a lateral shift by the shift amount calculated from the
detection result of the CIS 15, thereby correcting lateral
registration (shift control unit).
[0107] Referring to FIG. 13, if the shift unit 20 is angled by
.theta.relative to the conveying direction (rotation control unit),
the sheet P is deviated by X=Ltan.theta. in the direction
orthogonal to the conveying direction during its conveyance from
the pairs of registration rollers 12 to the pairs of timing rollers
13. This enables calculation of an optimum shift amount by adding X
to what is calculated as the gate angle adjustment amount.
[0108] In the sheet conveying device according to the embodiment of
the present invention described heretofore, the shift unit that
supports the gate members and the pairs of registration rollers can
be moved in the direction orthogonal to the sheet conveying
direction and the gate angle can be adjusted with a simple
configuration.
[0109] The shift unit includes the rollers on the drive side and
the driven side of the pairs of registration rollers and these
rollers on the drive side and the driven side can both be inclined,
which eliminates possibility of skew occurring during
conveyance.
[0110] The gate angle adjustment mechanism makes the adjustment
with the drive transmitting unit used as a pivot, thereby achieving
an easy adjustment mechanism. A lateral shift operation of the
shift unit can also be made even by adjusting the gate angle.
[0111] The lateral shift amount, the angle adjustment amount, and
the lateral shift amount that incorporates the deviation amount
during angle adjustment are obtained based on the detection result
of the detector to thereby drive the shift unit. This enables the
user to adjust the lateral shift position and the gate angle
according as he or she desires.
Second Embodiment
[0112] The following describes a sheet conveying device according
to another embodiment of the present invention. It is noted that
descriptions for similarities to the above-described embodiment
will be omitted.
[0113] As described in the first embodiment, use of the shaft 12a
of the pairs of registration rollers 12 as the adjustment shaft
achieves a maximum movable angle for the shift unit 20. Meanwhile,
referring to FIG. 14, preferably, the sheet conveying device 10
includes, in addition to the pairs of registration rollers 12, a
shaft 28 that penetrates the shift unit 20 and can be fixed to the
frame side plates 18A, 18B at right and left.
[0114] In this case, the gate angle can be adjusted by, for
example, moving the shaft 28 in the forward or backward direction
of the conveying direction from the outside of the frame side plate
18B, with one end of the shaft 28 as a pivot. In the example
illustrated in FIG. 14, a protrusion from the shaft 28 is moved by
an angle .theta..sub.2 in the conveying direction and then fixed in
position.
[0115] The shaft 28 may be fixed at a variably adjustable position
in the conveying direction in the frame side plate 18B as follows.
Specifically, the shaft 28 may have a groove 28a, for example, as
illustrated in (A) of FIG. 15; a bracket 29 is fitted in the groove
28a and the bracket 29 is fixed in the frame side plate 18B with,
for example, a screw 29a as illustrated in (B) and (C) of FIG. 15;
(B) is a side elevational view and (C) is a top view, illustrating
a condition in which the shaft 28 is fixed in the frame side plate
18B via the bracket 29. It is noted that, in (B) of FIG. 15,
reference numeral 18Ba denotes a threaded hole for the bracket 29
formed in the frame side plate 18B and reference numeral 18Bb
denotes a slot in which the position of the shaft 28 can be
adjusted.
[0116] At this time, preferably, the bracket 29 may, for example,
be graduated and the gate angle can be adjusted using the
graduations. In addition, similarly to the above-described first
embodiment, a rotation control driving unit calculates the gate
angle adjustment amount based on a detection result given by a CIS
15 and controls the leading end position of the shaft 28, thereby
setting a desired gate angle.
[0117] The shift position may be controlled by allowing the shift
unit 20 and the shaft 28 to be slidable through, for example, a
bearing and the shift amount may thereby be adjusted.
Alternatively, the shift amount may still be adjusted as follows:
specifically, the shift unit 20 and the shaft 28 are fixedly
mounted and the shaft 28 is adapted to have a plurality of grooves
28a, so that the bracket 29 is fitted selectively in one of the
grooves 28a.
Third Embodiment
[0118] The first embodiment has been described for an example in
which the fixing guide 24 journals the shaft 12a slidably in the
axial direction and inclinably through rotation control. As
illustrated in FIG. 16, preferably, the sheet conveying device 10
further includes a rotary plate 27 that rotates in operative
association with the shift unit 20 during the rotation control.
[0119] The example illustrated in FIG. 16 includes the rotary plate
27 and a guide unit (not illustrated) disposed at a lower portion
of the shift unit 20, the guide unit for guiding the shift motion
of the shift unit 20. The guide unit is disposed in parallel with
the shaft 12a so that the shift unit 20 is slidable in the
direction orthogonal to the conveying direction during
non-rotational control (e.g. FIG. 5) of the shift unit 20. The
guide unit may include, for example, a protrusion disposed on the
underside of the shift unit 20 and a recess formed in the rotary
plate 27. The foregoing arrangement allows the shift unit 20 to be
stably slidable (shift amount adjustment) even during an angle
adjustment.
[0120] Preferably, a guide plate 25 may also be provided in order
to reliably support rotation of the rotary plate 27.
[0121] According to the embodiments, it enables, with a simple
arrangement, the shift unit that supports the gate members and the
pairs of registration rollers to be moved in the direction
orthogonal to the sheet conveying direction and the gate angle to
be adjusted.
[0122] Although the invention has been described with respect to
specific embodiments for a complete and clear disclosure, the
appended claims are not to be thus limited but are to be construed
as embodying all modifications and alternative constructions that
may occur to one skilled in the art that fairly fall within the
basic teaching herein set forth.
* * * * *